ABSTRACT In studies using population controls, HIV infection has been associated with increased risk of cardiovascular disease (CVD). However, this risk may be partially explained by factors other than HIV or its treatment including higher rates of smoking, alcohol abuse, cocaine use, hepatitis C infection and renal disease. Equally important, major mechanisms of CVD among those with HIV likely differ from those without infection because lipid abnormalities occur abruptly--after initiation of combination antiretroviral therapy (CART), and because of inflammatory effects of HIV and HCV, toxic effects of alcohol and vasospasm due to cocaine. The Veterans Aging Cohort Study (VACS) is an ongoing, multicenter, prospective study of 3227 veterans with HIV infection and 3240 age/race/site matched HIV uninfected controls. Teamed with internationally recogized experts in CVD, we propose to supplement the rich clinical data available in this cohort with adjudicated CVD endpoints, and biomarkers and measures of CVD risk including: dyslipidemia, insulin resistance , markers of inflammation, cardiac structural and functional abnormalities, body composition changes, subclinical atherosclerosis, cardiac fitness, and alterations associated with thrombogenesis and fibrinolysis. With these enriched data we will be uniquely positioned to determine whether: 1) HIV infection is an independent risk factor for CVD endpoints and whether HCV, substance use and CART modify the association between HIV and CVD endpoints, 2) biomarkers and measures of CVD risk are increased among those with HIV infection and CART nonadherence, and 3) biomarkers and measures of CVD risk are increased among those with HCV infection and substance use. Importantly, we will adjust for both CART adherence and competing risk, since HIV infected individuals have a substantially higher mortality rate. The large, well characterized, older, predominantly minority patient sample with excellent longitudinal follow up and high prevalence of HCV and substance use, comprehensive pharmacy data, and established access to comprehensive electronic medical records are important leveraged strengths of this application. The strong CVD expertise, established analytic and mentoring skills of the VACS team, and a multi-PI plan incorporating a promising new investigator ensure that this proposal will effectively advance our understanding of CVD outcomes and mechanisms among HIV infected and uninfected individuals.